Views: 43 Author: Leapion laser Publish Time: 05-09-2023 Origin: https://www.leapion.com/
The principle of laser cutting
How the process of laser cutting happens?
The focused high-power-density laser beam irradiates the workpiece, causing the irradiated material to rapidly melt, vaporize, ablate or reach the ignition point, and at the same time blow off the molten material with the help of high-speed airflow, thereby realizing the cutting of the workpiece. Laser cutting is one of the thermal cutting methods.
Components of a laser cutter
The main part of the machine tool
The machine tool including the cutting work platform is the mechanical part that realizes the movement of the X, Y, and Z axes.
Laser generator
A device that generates a laser light source.
External optical path
It is used to reflect the laser beam in the required direction.
Numerical control system
Control the machine tool to realize the movement of the X, Y, and Z axes, and the output power of the laser source.
Stabilized power supply
It is connected among a laser source, CNC machine tool, and power supply system.
Cutting head
It mainly includes cavity, focusing lens seat, focusing mirror, capacitive sensor, auxiliary gas nozzle and other objects. Laser head is an important component of the fiber optic metal cutting machine, which is used to generate laser beam energy for cutting and it is similar to a human heart.
Operating table
It is used to control the working process of the entire cutting device.
Chiller
It is used to cool the laser generator.
Gas cylinder
It includes medium gas cylinder and auxiliary gas cylinder, and they are used to supplement industrial gas for laser oscillation and auxiliary gas for cutting heads.
Air compressor and air storage tank
They provide and store compressed air.
Air cooling dryer and filter
It is used to supply clean dry air to the laser generator and beam path to keep the path and reflector working normally.
Ventilation and dust removal machine
It exhausts the smoke and dust caused during processing and filters them to make the exhaust gas meet environmental protection standards.
Slagging machine
It removes the leftovers and wastes caused during processing.
What are the types of laser cutters?
It depends on how you classify it.
1. If classified by laser source, they can be divided into
(1) Solid-state laser source.
Solid-state laser sources are divided into ruby lasers, YAG, etc.
(2) Semiconductor laser source.
(3) Liquid laser source.
(4) Gas laser source and CO2 laser source.
2. According to the structure of laser cutters, it can be divided into
(1) Desktop laser cutter
This type of laser cutter is the most common. It puts the laser on one side and transmits it to the laser cutting head through the external optical path. The processing range is generally 1, 53M and 24M.
According to integral structure, it can be divided into cantilever type, gantry type and hybrid type.
Many brands of laser cutters, such as TRUMPF, Bystronic, Prima, MAZAK, etc., are mostly desktop laser cutting machines.
The desktop mode is mainly used for sheet metal processing. Many industries such as elevator manufacturing, electrical switchgear, food machinery and other industries that mainly process thin plates apply desktop laser cutters.
3. If divided according to the cutting workpiece. The types are
(1) Metal laser cutters. The power of the laser source is generally relatively high.
(2) Non-metallic laser cutters. The power of the laser is generally very low.
(3)There are also laser cutters processing sheets and pipes.
Laser cutting process
1. Vaporization cutting
During this laser cutting process, the surface temperature of the material rises to the boiling point so fast that it is enough to avoid melting caused by heat conduction, so one part of the material is vaporized into steam and disappears, and the other part of the material is ejected from the bottom of the slit by the auxiliary gas. Very high laser powers are required in this case.
To prevent material vapor from condensing on the slit wall, the thickness of the material should not exceed the diameter of the laser beam too much. This process cannot be used for some materials, such as wood and certain ceramics, which will not melt and are therefore less likely to allow the material vapor to recondense.
Additionally, these materials typically need thicker cuts. In laser vapor cutting, optimal beam focusing depends on material thickness and beam quality. Laser power and heat of vaporization have a limited influence on the optimal focus position. When the thickness of the plate is constant, the maximum cutting speed is inversely proportional to the gasification temperature of the material. The required laser power density is greater than 108W/cm2 and depends on the material, cutting depth and beam focus position.
2. Laser fusion cutting
In this laser-cutting process, the workpiece is partially melted and the molten material is ejected by means of airflow. Because the transfer of the material occurs only when it is in the liquid state, the process is called laser fusion cutting.
The laser beam coupled with high-purity inert cutting gas drives the molten material out of the kerf, but the gas itself does not participate in the cutting. Laser fusion cutting can achieve higher cutting speed than gasification cutting. The energy required for gasification is generally higher than that required to melt the material.
In laser fusion cutting, the laser beam is only partially absorbed. The maximum cutting speed increases with the increase of laser power and decreases almost inversely proportional to the increase of sheet thickness and material melting temperature. In the case of certain laser power, the limiting factor is the air pressure at the kerf and the thermal conductivity of the material. Laser fusion cutting can obtain oxidation-free cuts on iron materials and titanium metals. The laser power density that produces melting but not up to gasification is between 104W/cm2 and 105W/cm2 for steel materials.
3. Oxidation melting cutting (laser flame cutting)
Fusion cutting generally uses inert gas. If it is replaced by oxygen or other active gas, the material is ignited under the irradiation of the laser beam, and a violent chemical reaction occurs with oxygen to generate another heat source, which further heats the material.
Due to this effect, higher cutting rates can be obtained with this method than with fusion cutting for the same thickness of structural steel. On the other hand, this method may have poorer cut quality than fusion cutting. It produces wider kerfs, noticeable roughness, increased heat-affected zone, and poorer edge quality. Laser flame cutting is bad for precision models and sharp corners (danger of burning off sharp corners). Lasers in pulsed mode can be used to limit thermal effects, and the power of the laser determines the cutting speed. In the case of certain laser power, the limiting factors are the supply of oxygen and the thermal conductivity of the material.
4. Controlled fracture cutting
For brittle materials that are easily damaged by heat, high-speed and controllable cutting is needed, which is called controlled fracture cutting. The main content of this cutting process is that the laser beam heats a small area of brittle material, causing a large thermal gradient and severe mechanical deformation in this area, resulting in the formation of cracks in the material. As long as a uniform heating gradient is maintained, the laser beam can direct cracks in any desired direction.
The above is a brief introduction to laser cutters, if you need more information, please contact us.
